The present invention generally relates to methods and means for controlling motors. More specifically, the invention relates to methods and means for controlling operation of permanent split capacitor motors.
Shredders are devices, as the nomenclature implies, that are used to shred items, for example, by slicing. To that end, shredders that slice include a plurality of blades driven by a motor, usually a permanent split capacitor motor. Typically they are used to shred paper-based products, but in some installations they are also used to shred a diversity of items, such as garbage.
Paper shredders are often used to shred sensitive documents so that the documents cannot be easily reassembled and thus the matter therein recognized or read. Typically, when more sheets of paper are fed into the shredder than the shredder can slice at one time, the shredder will jam. In my commonly assigned allowed U.S. patent application, Ser. No. 07/970,070, which issued Oct. 12, 1993 as U.S. Pat. No. 5,252,904, provides an arrangement wherein the slicing blade motor is automatically reversed to eject the paper, thereby relieving the jamming. There are other arrangements wherein the :motor can be coupled to the blades by a slip clutch or the like and be permitted to slip.
It can be appreciated that it is advantageous to increase the capacity of a shredder so that the throughput, including the number of items of papers that can be shredded at one time, can be increased. Typically, the throughput is increased by increasing the size of the motor used to run the blades that affect the shredding. However, simply increasing the size of the motor is not always a practical option inasmuch as there may be space limitations and/or cost limitations involved.